Mercury Systems CEO sells 27,680 shares for taxes

MERCURY SYSTEMS INC (MRCY) reported insider transactions by Chairman, President & CEO William L. Ballhaus involving company common stock.

Rhea-AI Filing Summary

MERCURY SYSTEMS INC (MRCY) reported insider transactions by Chairman, President & CEO William L. Ballhaus involving company common stock. On August 17–18, 2026, he sold a total of 27,680 shares of common stock in open-market or private transactions at per-share prices of $109.9509 and $111.3577. Footnotes state these sales were part of a sell-to-cover program to satisfy tax withholding obligations upon the vesting of stock awards, and the reported prices are the per‑share prices attributed to sales made on behalf of all program participants on those dates. The filing also lists post‑transaction indirect holdings of 1,403 shares in a 401K Plan and 7,066.173 shares held by Milestone Road Holdings, LLC.

Insider Trade Summary

Net Seller: 27,680 shares

Net Sell 4 txns

Insider Ballhaus William L

Role Chairman, President & CEO

Sold 27,680 shs ($3.08M)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	24,144	$111.3577	$2.69M
Sale	Common Stock F1, F2	3,536	$109.9509	$389K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 277,009.325 shares (Direct); Common Stock — 1,403 shares (Indirect, 401K Plan); Common Stock — 7,066.173 shares (Indirect, By Milestone Road Holdings, LLC)

Footnotes (2)

1. F1. Represents shares sold as part of a sell-to-cover program to satisfy tax withholding obligations upon the vesting of stock awards.
2. F2. Represents the per share price attributed to sales of shares on behalf of all participants under the sell-to-cover program on the transaction date indicated.

Key Figures

Shares sold August 18, 2026: 24,144 shares Price August 18, 2026 sale: $111.3577 per share Shares sold August 17, 2026: 3,536 shares +4 more

7 metrics

Shares sold August 18, 2026 24,144 shares Common stock sale at $111.3577 per share

Price August 18, 2026 sale $111.3577 per share Attributed per‑share price under sell-to-cover program

Shares sold August 17, 2026 3,536 shares Common stock sale at $109.9509 per share

Price August 17, 2026 sale $109.9509 per share Attributed per‑share price under sell-to-cover program

Total shares sold 27,680 shares Net sell transactions reported across both days

Indirect 401K holdings 1,403 shares Common stock held indirectly in 401K Plan after transactions

Indirect LLC holdings 7,066.173 shares Common stock held indirectly by Milestone Road Holdings, LLC after transactions

Key Terms

sell-to-cover program, tax withholding obligations, 401K Plan, indirect

4 terms

sell-to-cover program financial

"Represents shares sold as part of a sell-to-cover program to satisfy tax"

tax withholding obligations financial

"to satisfy tax withholding obligations upon the vesting of stock awards"

401K Plan financial

"total_shares_following_transaction 1403.0000 ... nature_of_ownership 401K Plan"

A 401(k) plan is an employer-sponsored retirement savings account that lets workers set aside part of their paycheck into investments, often with tax breaks and sometimes with matching contributions from the employer. Think of it as a workplace piggy bank that grows through employee contributions, optional company top-ups, and market returns; it matters to investors because it shapes household retirement security, drives large flows of money into public markets, and affects a company’s compensation costs and ability to attract and keep talent.

indirect financial

"ownership_type indirect ... nature_of_ownership By Milestone Road Holdings, LLC"

FAQ

What insider stock transactions did MRCY CEO William L. Ballhaus report on this Form 4?

William L. Ballhaus reported sales totaling 27,680 shares of Mercury Systems common stock on August 17–18, 2026. The transactions were coded as open‑market or private sales and tied to tax withholding on vested stock awards.

At what prices were the MRCY shares sold in William L. Ballhaus’s August 2026 Form 4?

The reported per‑share prices were $109.9509 for 3,536 shares on August 17, 2026, and $111.3577 for 24,144 shares on August 18, 2026. Footnotes clarify these are prices attributed under a sell‑to‑cover program.

Why did the MRCY CEO sell 27,680 shares according to this Form 4?

The filing states the 27,680 shares were sold under a sell-to-cover program to satisfy tax withholding obligations upon vesting of stock awards. The shares were sold on behalf of participants to cover those tax liabilities.

What indirect MRCY shareholdings does William L. Ballhaus report after these transactions?

After these transactions, the Form 4 lists indirect holdings of 1,403 shares in a 401K Plan and 7,066.173 shares held by Milestone Road Holdings, LLC. These figures represent post‑transaction positions as of August 17, 2026.

Does this MRCY Form 4 indicate any derivative security exercises or gifts?

No. The transaction summary shows two sales of common stock and no derivative exercises, gifts, or restructuring transactions reported in this Form 4. The derivative transaction count and gift count are both zero.

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Available on EDGAR 08/19/2026 - 06:25 PM Accepted by SEC EDGAR 08/19/2026 - 06:24 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Ballhaus William L

(Last) (First) (Middle)

50 MINUTEMAN ROAD

(Street)

ANDOVER MASSACHUSETTS 01810

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
MERCURY SYSTEMS INC [ MRCY ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chairman, President & CEO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/17/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/17/2026		S		3,536(1)	D	$109.9509(2)	301,153.325	D
Common Stock	08/18/2026		S		24,144(1)	D	$111.3577(2)	277,009.325	D
Common Stock								1,403	I	401K Plan
Common Stock								7,066.173	I	By Milestone Road Holdings, LLC

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Represents shares sold as part of a sell-to-cover program to satisfy tax withholding obligations upon the vesting of stock awards.

2. Represents the per share price attributed to sales of shares on behalf of all participants under the sell-to-cover program on the transaction date indicated.

	/s/ Douglas Munro, attorney-in-fact	08/19/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)